/Engine/Source/Editor/UnrealEd/Public/BaseWidgetBlueprint.h
Returns collection of widgets that represent the 'source' (user edited) widgets for this blueprint - avoids calling virtual functions on instances and is therefore safe to use throughout compilation.
[TArray](API\Runtime\Core\Containers\TArray)< class [UWidget](API\Runtime\UMG\Components\UWidget) * > GetAllSourceWidgets()